In the year 1778 he was employed in an interest ing investigation of the mutual adhesion of the sur faces of solids and fluids, a class of phenomena of -which the mathematical theory was never at all un derstood, until the publication of an essay on the Cohesion of Fluids in the Philosophical Transactions, soon after the beginning of this century, in which the laws of capillary action are extended to a complete analogy with all the experiments of M. de Morveau, as well as those of Taylor and Achard of a similar nature. He succeeded, about the same time, in dis covering a mode of destroying the contagious va pours of pestilential diseases, by fumigation with the muriatic acid gas; be afterwards found the oxymu. riatic acid, or pure chlorine, still more effectual ; and it does not appear that the nitric acid, afterwards proposed in England, has any advantages over either of these substances.
M. de Morveau's anxious desire to cooperate in the promotion bf chemical knowledge induced him to make a new exertion in its favour, by undertak ing, in 1776, to deliver a public and gratuitous course of lectures as a regular professor of the science, au thorised by the approbation and encouragement Of his brother magistrates at Dijon. He soon afterwards wrote some essays on the peculiar characters of the carbonic acid, and he strenuously combated the po pular prejudice, which prevailed, .against the intro duction of conductors, for preserving buildings from lightning. He established a large manufactory of nitre, which was afterwards conducted by Mr Courtois, the father of the Mr Courtois that discovered iodine. From chemistry he.naturally diverged into the study of mineralogy, and, in 1777, he made a tour through the province of Burgundy, with a view to the examination of all its productions ; and he ac tually discovered a rich lead mine, though, for want of coal, it was impossible to derive much benefit from it. He also found a white variety of the emerald in the same province, as well as some combinations of barita, and he invented a new method of obtaining the pure barite from its sulphate.
He had long been intimately acquainted with the Count de Baron and with Malesherbes, both persons distinguished by elegance of taste; the one in science, the other in general literature. In 1779 and 1780 he enlarged his connexions among the men of letters resident at Paris, and he was induced by Panckoucke, the bookseller, to undertake the chemical department of the Encydop6die Mithodique : but it was six years before the Dictionary of Chemistry appeared ; the articles relating to pharmacy and metallurgy were supplied by Maret and Duhamel. In the
progress of this work he found himself compelled to disbelieve the existence of phlogiston as a distinct principle of inflammability, though at the beginning he had defended the doctrines of the old school. But he soon became one of the most zealous advocates of the new theory; and he contri buted very much to its general introduction by the active part which he took in the arrangement of a new nomenclature. His proposals were at first thought objectionable by many of the members of the Aca demy of Sciences ; but they soon became generally adopted throughout Europe c and the system was without doubt of great use for a time, so far as it as sisted the memory and the imagination in retaining the discoveries and comprehending the theories which had so much of novelty to make them interesting. Among the original matter contained in the Diction ary were some researches on the nature of steel, which coincided in their results with those of Monge, Vandermonde, and Berthollet, made about the same time, but published somewhat earlier. The whole volume was received in the most flattering manner by all the lovers of chemistry ; but it was not till 1791, that the author's ambition was gratified by the award of the Academy of Sciences, adjudging him a prize of 2000 francs, which had been allotted to the most useful work that should appear in the course of the year. The prize, however, be begged to offer to the exigencies of the state, which were then very urgent. The Dictionary was afterwards ably con tinued by M. de Fourcroy.
In the meantime, he condescended to appear as the translator of the Opscala of Bergman, which be illustrated by notes. The example was followed by Madame Picardet, and by others of his friends, who were zealous for the promotion of science ; so that the French chemists were speedily made acquainted, by these means, with the labours of all their contem poraries in different parts of the world. In the year 1787, Mr Guyton applied his speculations to a practical purpose, in establishing a manufactory of soda from common salt, exposed to the atmosphere, with a large proportion of lime, the soda slowly efflo rescing as a carbonate. It was in the same year that, having published his Collection of Pleadings, he finally resigned his office at the bar, in order ;hat the whole of his time might be devoted to the pur suit of science.